In a preview clip of Sunday's Kendra, the new mom (and recent Us Weekly cover girl) admits it isn't easy slipping into a swimsuit months after giving birth.

"I was doing a lot of suckin' in, let me tell you!" the E! reality star, 24, says at a recent magazine shoot (watch clip, above).

Her spirits get better when her 3 1/2-month-old son Hank IV joins her as she poses in a bikini.

"Baby Hank is a natural in front of the cameras!" she says. "The Gerber baby better watch out!"